It is important in medicine to identify the site of pathology in order to properly screen for and/or treat a disease. Tumor screening for the presence of tumors (e.g. for breast cancer, cervical cancer, colon cancer, prostate cancer, etc.) is very common. Some of the difficulties with tumor screening are expense, patient's time, physician's time, and accuracy. Also, many of the screening tests are not particularly accurate. For example, testing for prostate cancer using serum acid phosphatase or prostate specific antigen (PSA) is non-specific, and elevation of the marker in healthy individuals can be cause for an unnecessary surgery, a prostate biopsy. An additional example is MRI screening for breast tumors, whose value has recently been questioned for both insensitivity and occasional misinterpretation. In addition, the presence or absence of sentinel (metastatic) nodes is critical for the optimal treatment of breast cancer. Low grade chondrosarcomas are notoriously difficult to read by the pathologist, and frequently have to be sent to multiple institutions for a diagnostic consensus. All of these examples suggest the need for improving detection for all benign, malignant, primary and secondary tumors. A rapid and non-invasive method of localizing tumors would aid immensely in diagnosing and treating the underlying cause. The growing tendency to understand tumors at the molecular level may also be guided by such improved non-invasive methods.
Localization of pain is another area where identifying the site of pathology is important for treatment; however, such localization is often not straightforward. The unpleasant sensation of pain serves as an indicator of a disease or pathological state. Pain often occurs at the site of pathology, and can be a helpful guide in determining diagnosis and appropriate treatment. However, in many cases, the area where a patient experiences pain may not be coincident with the area where the actual pathology has occurred. A classic example is sciatica, where pressure on the sciatic nerve due to a herniated disc in the lower spine can result in a sensation of pain in the leg, at a significant distance from the site of pathology. Another example is the difficulty in diagnosing pain in the chest or thorax, which can arise from multiple causes, such as cardiac ischemia, gastroesophageal reflux, or pulmonary embolism. In such cases, differential diagnosis requires a systematic process of elimination through tests and procedures until the cause and/or location of pathology is identified.
Screening for infectious diseases, particularly when a patient is still asymptomatic, also poses difficulties. Medicaments and methods for such screening would prove useful in limiting outbreaks of diseases; early treatment of infected individuals; and avoiding unnecessary treatment or isolation for individuals who are suspected of being infected, but who in actuality have not been infected, by a disease.
Because pathology is often accompanied by inflammation at the site of the pathology (which is not necessarily the site where pain is experienced), rapid and non-invasive methods of localizing inflammation in a patient experiencing pain would aid immensely in diagnosing and treating the underlying cause of the pain.